1. Field of the Invention
The present invention relates to an inverter for converting DC voltage to AC voltage and outputting the AC voltage.
2. Description of the Related Art
In the case of connecting an electronic device having a so-called capacitor-input-type rectifier including a capacitor on its input side as a load on an inverter for converting DC voltage to AC voltage, at the time of rapidly charging the capacitor to start the inverter, there is a case that excessive rush current having a timing waveform of output current as shown in FIG. 7 as an example flows. When such excessive rush current flows, a semiconductor device or the like on a current path may be broken down or a mechanical contact such as a relay contact may be melted.
Japanese Unexamined Patent Application Publication No. 2002-335678 discloses an inverter in which generation of excessive rush current upon start of an inverter is prevented by making output AC voltage having a sine wave always start from 0V at the time of starting the inverter as shown in FIG. 8.
Japanese Patent No. 3,362,666 also discloses an inverter. AC output current from the inverter is detected at any time. In the case where the AC output current becomes larger than a predetermined first threshold, before the AC output current reaches a second threshold larger than the first threshold, flow of excessive current is allowed for a while.